Resistive switching elements can operate as viable alternatives to various memory cell technologies, such as metal-oxide semiconductor (MOS) type memory cells employed for electronic storage of digital information. Models of resistive-switching memory devices provide some potential advantages over non-volatile FLASH MOS type transistors, including smaller die size, higher memory density, faster switching (e.g., from a relatively conductive state to a relatively non-conductive state, or vice versa), good data reliability, low manufacturing cost, and other advantages.
In particular, resistive random access memory (RRAM) can hold substantial advantages over competing technologies in the semiconductor electronics industry, such as for high density non-volatile storage. An RRAM device has an insulator layer that is provided between a pair of electrodes and exhibits electrical pulse induced hysteretic resistance switching effects. Filaments can be formed between the electrodes by a diffusion and (or) drift of ions that reduce or increase the resistance of the structure and remain after being induced, in which gives the device a non-volatile characteristic in a programmed state. The ions can then be removed and the cell be in an erase state by a reverse flow of the ions, and thus, enable a controllable resistive nature. However, the RRAM devices are manufactured to operate in either a unipolar modality or in a bipolar modality for programming and erasing.